“I have some ideas,” Yeun teased. “But I heard if you put it out there, you’ll never get it, so I’ll keep it close to my chest.”
It wouldn't surprise me if Marvel cast him as Sunfire in the X-Men stuff, but that would be problematic as Sunfire is Japanese and Yeun is Korean. But I guess they could just re-make the character as Korean... why not?
I think once the X-Men enter the scene you have a HUGE pile of characters to choose from. I'm not super familiar with Sunfire but from what I do know his Japanese background is an important part of the character. I'd be hesitant to just remove it.
However as an ancestor of Sunfire that could be fine.
I think "Amadeus Cho" works of you're looking for a Korean American role. Although realistically I don't think Yeun is actually good for that role. I think he is a little too old and while I know he can play that character (since Invincible is roughly the style we're going for) I don't see it working in live action.
I think as an actor there are A LOT of roles he could fit into. I do wish we got to see him in a more villainous role since that is one I don't quite see when I think of him. In any case I expect he'll find an alternative role soon enough.
It's amazing when you consider the X-Men started as a base of six characters then ballooned out into hundreds. Definitely room for all sorts of casting.